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Ride the Rock Cycle:
Will you become a mine?
Notes for Teachers
The rock cycle is used to help students understand the dynamic nature of the rock and mineral
materials that make up the crust and mantle of the Earth. The natural processes that take place on,
below, and above the surface of the Earth move materials through a variety of cycles: water, nitrogen,
carbon, and rock. This activity is designed to teach your students about the rock cycle and the
processes that move rocks through this cycle. By moving around the room from station to station,
they will learn that the rock cycle is not linear and that all rocks don’t follow the same paths. They
will also come to understand that the rocks and minerals that we mine for items we use in our daily
lives did not form everywhere; they formed in particular environments at particular times in the
geological past.
This activity is similar to “ride the rock cycle” activities that you may have used in the past. It is
different in that it adds time to the movement from one station to another. Because the students are
moving through the rock cycle in geologic time, the numbers are large numbers of years. The setup
should make it easy for students to do this even without a calculator. Having time added to the
activity permits the students to construct a geologic history of the travels the atoms in the rocks make
through the rock cycle.
Time to complete: two class periods or possibly one, if on a block schedule. It is good to plan for
two days as that will provide time for the teams to share their results and have some discussion about
the nature of economic accumulations of rocks and minerals (ores). Which type of ore was formed
most frequently? How many teams did not have the right age and type of rock to form one of the ore
deposits? Were deposits created then destroyed by subsequent processes that changed them into
another type of rock?
Prerequisites: It is helpful if the students have had prior instruction in the different rock types and
how they are formed. A one-page diagram helps to explain the processes involved in the rock cycle.
In this activity, the classic three rock types (igneous, metamorphic, and sedimentary) are subdivided
into volcanic (extrusive igneous), intrusive igneous, metamorphic, clastic sedimentary, and chemical
sedimentary rocks. An understanding of plate tectonics is also helpful.
Materials:
 12 Station labels (copied onto card stock or laminated for repeated use)
 12 copies of the one-page diagram of the rock cycle (copied onto card stock or laminated)
 Rock-cycle data sheets (one for each two-person team of students)
 Geologic history sheet (one for each two-person team of students)
 Pairs of six-sided dice (one pair for each two-person team of students)
 Optional samples of rocks and ores.
Page 1
Possible answers to some of the questions:
1. Where did you spend the most time? Answers vary depending on the data.
2. Why do scientists call the rock cycle a cycle? Cycles are series of events that repeat themselves,
not always in the same order and not always in the same sequence, as in the case of the rock cycle. In
the rock cycle there are natural processes that move the rock material through changes from one rock
type to another. The rock cycle is considerably slower than other cycles on earth: for example the
water cycle is much faster.
3. Where do weathering and erosion occur? Near or on the earth’s surface.
4. List the processes that move the rocks through the rock cycle. Compaction and cementation, high
temperature and pressure, melting, cooling and crystallizing, weathering and erosion, dissolution and
precipitation.
5. Explain the forces or sources of energy that create these processes. They are the forces of nature:
wind, water, gravity, temperature and temperature changes, light, magnetism. These forces move
materials through the rock cycle. The Sun provides most of the energy for surface processes.
Radioactive decay, and, to a lesser extent, internal heat from the formation of the Earth, drive most of
the other processes.
6. If you were at the Earth’s surface, what type of rock were you when you got there? Answers vary
depending on their data.
7. Look at your data. Pay attention to where you are located geographically (either Alaska, Hawaii,
or the western, central, or eastern conterminous United States. Could you have formed any of the
above ore deposits? If so, which ones? Answers vary depending on the data. For Example 1, no; the
volcanic rock is too young to have ore deposits; the metamorphic rock is also too young for crushed
stone (gneiss) and too old for Carlin-type gold deposits; and the intrusive igneous rock is too old for
porphyry copper or molybdenum deposits and too young for platinum or rare earth elements. For
Example 2, yes; the chemical sedimentary rock (youngest rock) could have gypsum in the western
U.S. or phosphate deposits in the eastern U.S. The middle, clastic sedimentary rock could have had
coal or uranium, and the oldest sedimentary rock could have had a number of deposits (limestone,
barite, gypsum, potash, salt, coal, uranium, lead or zinc), but these middle and oldest rocks were later
eroded. Also note, that actually having an ore deposit of a particular type depends on where you are
(e.g., eastern, central, or western U.S.) as well as the appropriate age of rock.
8. Assuming that you did form an ore deposit, was the deposit preserved and located near the surface
so that it can now be mined? Or was the deposit weathered and eroded away in the years after it
formed? Answers vary, depending on data, but the only deposits that can be mined are the ones
contained in the youngest rock, as that one still exists.
9. Take a survey of your class and list the number and types of deposits formed through this activity
by everyone in the class.
10. Did this exercise help you understand how infrequently economic accumulations of rocks and
minerals occur on earth? Explain: Generally not many rocks actually end up being an economic
deposit. Rocks and minerals are where they are because of the forces of nature; we can’t put them
Page 2
where we would like them to be. Therefore, we must mine them in place, which can be controversial.
We have choices over where to build a city or a road or a farm field, we do not have choices when it
comes to the locations of natural resources from the crust. We can’t mine it where it doesn’t exist.
And if we don’t mine, how do we live? Our lives depend on mining for food, housing, clothing,
transportation, communication, lighting, heating/cooling, health and safety. Consider the average life
span in the Stone Age (when they mined stones for tools): 25 years. Now consider the average life
span in the United States today: 85 years (because of modern health care, clean water and access to
good food, which are all a result of the rocks and minerals we take from the Earth’s crust). If we
don’t mine in one place, the mineral resources needed for society to function will be mined
somewhere else. Recycling helps, but as long as global population and standards of living continue
to grow, recycling won’t replace mining.
11. What is the probability that on your first roll of the dice you stay at the rock at which you start?
The answer is 1/3 or 0.3333 or 33.33% for all four rocks.
For the Intrusive Igneous Rock, rolls of 4, 7, or 10 all have “Go to” as Intrusive Igneous Rock, such
that the cumulative probability is, respectively, 3/36 + 6/36 + 3/36 = 12/36 = 1/3.
For the Volcanic Rock, rolls of 4, 8, 10, or 12 all have “Go to” as Volcanic Rock, such that the
cumulative probability is, respectively, 3/36 + 5/36 + 3/36 + 1/36 = 12/36 = 1/3.
For the Sedimentary Rock, rolls of rolls of 4, 7, or 10 all have “Go to” as Sedimentary Rock, such
that the cumulative probability is, respectively, 3/36 + 6/36 + 3/36 = 12/36 = 1/3.
For the Metamorphic Rock, rolls of rolls of 4, 7, or 10 all have “Go to” as Metamorphic Rock, such
that the cumulative probability is, respectively, 3/36 + 6/36 + 3/36 = 12/36 = 1/3.
12. What is the least number of rolls of the dice that are needed to complete this exercise? It will
help to examine the rock-cycle diagram and to remember that you also must roll for the number of
years at each station. Examining the rock-cycle diagram, there are Nine. For example, starting at
Volcanic Rock, the first roll is for the number of years to stay there. The second roll would take you
to High Temperature & Pressure, and the third roll is for the number of years there. The fourth roll
takes you Metamorphic Rock (second rock), and the fifth roll is for the number of years there. The
sixth roll takes you to High Temperature & Pressure again, and the seventh roll is for the number of
years there. The eighth roll takes you back to Metamorphic Rock again (third rock), and the final,
ninth roll is for the number of years there. There are three other scenarios that require only nine rolls.
These possible shortest paths are listed in Table 3.
Table 3. Scenarios for completing the exercise with the least number of rolls of the dice.
Start at
Go to
Go to
Go to
Go to
Intrusive Igneous Rock
Volcanic Rock
Sedimentary Rock
Metamorphic Rock
High T & P
High T & P
High T & P
High T & P
Metamorphic Rock
Metamorphic Rock
Metamorphic Rock
Metamorphic Rock
High T & P
High T & P
High T & P
High T & P
Metamorphic Rock
Metamorphic Rock
Metamorphic Rock
Metamorphic Rock
______________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________
For the next question, possibly for extra credit, students should calculate the probabilities of each of
these scenarios. Note that the probabilities for all four of these scenarios are less than 1%; it is
unlikely that many students will complete the exercise with few rolls.
Page 3
Extra Credit
13. For which starting rock do you have the highest probability of completing this exercise with the
least number of rolls? Intrusive Igneous Rock. What path does your atom take for this highest
probability? Intrusive Igneous Rock to High Temperature & Pressure, then to Metamorphic Rock,
then back to High Temperature & Pressure, then, finally, back to Metamorphic Rock.
Ignoring the five rolls needed to determine the numbers of years you stay at each station, there are
four rolls involved in moving from one station to the next when completing the exercise with the least
number of rolls.
If starting at Intrusive Igneous Rock, the least number of rolls could be from Intrusive Igneous Rock
to High Temperature & Pressure, then to Metamorphic Rock (for the second rock), then back to
High Temperature & Pressure, then finally back to Metamorphic Rock again (for the third rock).
The possible rolls and probabilities for these steps are
Roll 2, 5, or 9, for which Probability (Intrusive Igneous Rock to High Temperature & Pressure) =
1/36 + 4/36 + 4/36 = 9/36 = 1/4.
Roll 4, 7, or 10, for which Probability (High Temperature & Pressure to Metamorphic Rock) =
3/36 +6/36 + 3/36 = 12/36 = 1/3.
Roll 8 or 12, for which Probability (Metamorphic Rock to High Temperature & Pressure) =
5/36 + 1/36 = 6/36 = 1/6.
Therefore the cumulative probability of these four rolls occurring in this sequence equals
1/4 x 1/3 x 1/6 x 1/3 = 1/216 = 0.0046 = 0.46%.
If starting at Volcanic Rock, the first roll could be to go from Volcanic Rock to High Temperature &
Pressure, then from High Temperature & Pressure to Metamorphic Rock, then back to High
Temperature & Pressure, then finally back to Metamorphic Rock. The possible rolls and
probabilities for these steps are:
Roll 7, for which Probability (Volcanic Rock to High Temperature & Pressure) = 6/36 = 1/6.
Roll 4, 7, or 10, for which Probability (High Temperature & Pressure to Metamorphic Rock) =
3/36 +6/36 + 3/36 = 12/36 = 1/3.
Roll 8 or 12, for which Probability (Metamorphic Rock to High Temperature & Pressure) =
5/36 + 1/36 = 6/36 = 1/6.
Therefore, the cumulative probability of these four rolls occurring in this sequence equals
1/6 x 1/3 x 1/6 x 1/3 = 1/324 = 0.0031 = 0.31%.
If starting at Sedimentary Rock, the least number of rolls is could be from Sedimentary Rock to
High Pressure & Temperature, then to Metamorphic Rock (second rock), then back to High
Temperature & Pressure, then to Metamorphic Rock again (third rock). The possible rolls and
probabilities for these steps are
Roll 8 or 12, for which Probability (Sedimentary Rock to High Temperature & Pressure) =
5/36 + 1/36 = 1/6.
Roll 4, 7, or 10, for which Probability (High Temperature & Pressure to Metamorphic Rock) =
3/36 +6/36 + 3/36 = 12/36 = 1/3.
Roll 8 or 12, for which Probability (Metamorphic Rock to High Temperature & Pressure) =
5/36 + 1/36 = 6/36 = 1/6.
Therefore the cumulative probability of these four rolls occurring in this sequence equals
1/6 x 1/3 x 1/6 x 1/3 = 1/324 = 0.0031 = 0.31%.
Page 4
If starting at Metamorphic Rock, the least number rolls could be from Metamorphic Rock to High
Temperature & Pressure, then back to Metamorphic Rock (for the second rock), then again to High
Temperature & Pressure, then finally back to Metamorphic Rock (for the third rock). The possible
rolls and probabilities for these steps are:
Roll 8 or 12, for which Probability (Metamorphic Rock to High Temperature & Pressure) =
5/36 + 1/36 = 6/36 = 1/6.
Roll 4, 7, or 10, for which Probability (High Temperature & Pressure to Metamorphic Rock) =
3/36 +6/36 + 3/36 = 12/36 = 1/3.
Therefore the cumulative probability of these four rolls occurring in this sequence equals
1/6 x 1/3 x 1/6 x 1/3 = 1/324 = 0.0031 = 0.31%.
The probabilities are summarized in Table 4.
Table 4. Probabilities for scenarios for completing the exercise with the least number of rolls of
the dice.
Start at
Go to
Go to
Go to
Go to
Intrusive Igneous Rock
Volcanic Rock
Sedimentary Rock
Metamorphic Rock
High T & P
High T & P
High T & P
High T & P
Metamorphic Rock
Metamorphic Rock
Metamorphic Rock
Metamorphic Rock
High T & P
High T & P
High T & P
High T & P
Metamorphic Rock
Metamorphic Rock
Metamorphic Rock
Metamorphic Rock
Probability
0.46%
0.31%
0.31%
0.31%
______________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________
Additional Extra Credit
14. Starting as an atom in a volcanic rock, what is the probability that you will
a. be there for 50,000 years,
Roll 6 or 12; P = (5+1)/36 = 1/6
b. then go to the Earth’s Surface,
Roll 2, 5 or 9; P = (1+4+4)/36 = 1/4
c. be there for 500,000 years,
Roll 7 or 10; P = (6+3)/36 = 1/4
d. then go to Sediments,
Roll 3, 5 or 7; P = (2+4+6)/36 = 1/3
e. be there for 500,000 years,
Roll 6 or 12; P = (5+1)/36 = 1/6
f. then go to Compaction and Cementation,
Roll 3, 5 or 10; P = (2+4+3)/36 = 1/4
g. be there for 10,000,000 years,
Roll 5 or 11; P = (4+2)/36 = 1/6
h. then go to Sedimentary Rock (clastic),
Roll 2,4,5,9 or 11; P = (1+3+5+4+2)/36 = 5/12
i. be there for 100,000,000 years,
Roll 7; P = 1/6
j. stay there (at Sedimentary Rock) on the next roll, Roll 4, 7 or 10; P = (3+6+3)/36 = 1/3
k. be there for 100,000,000 more years,
Roll 7; P = 1/6
l. stay there (at Sedimentary Rock) on the next roll, Roll 4, 7 or 10; P = (3+6+3)/36 = 1/3
m. be there for 100,000,000 more years,
Roll 7; P = 1/6
n. then go to High Temperature & Pressure,
Roll 8 or 12; P = (5+1)/36 = 1/6
o. be there for 100,000,000 years,
Roll 3, 5 or 10; P = (2+4+3)/36 = 1/4
p. then go to Metamorphic Rock, and, finally,
Roll 4, 7 or 10; P = (3+6+3)/36 = 1/3
q. be there for 50,000,000 years?
Roll 7; P = 1/6
That is, what is the overall probability of all these steps occurring in this sequence?
1/6 x ¼ x ¼ x 1/3 x 1/6 x ¼ x 1/6 x 5/12 x 1/6 x 1/3 x 1/6 x 1/3 x 1/6 x 1/6 x ¼ x 1/3 x 1/6 = 1.2 x 10-11 =
0.000000000012 = 0.0000000012%.
Note that this is a small number, which reinforces the fact that many ore deposits are rare relative to the rocks
in which they typically occur. A combination of geological processes, at the right place and time, is necessary
to form an ore deposit.
Page 5
Example 3 is one scenario of rolls of the dice by which these steps could have occurred.
This is a practical example. In the end, you will be an atom in a Metamorphic Rock, which, upon
examination of Table 1 in the Students’ Handout, is the right age to have a Carlin-type gold deposit.
This type of ore deposit is named for the town of Carlin, Nevada, near which several of these types of
deposits occur. Similar deposits occur in Utah and other parts of the world. The ones in the western
United States formed by hot water, laden with gold and sulfur and heated by Eocene magmas related
to subduction of oceanic crust beneath the North American Plate. The hot water also altered the
sedimentary host rocks by dissolving some minerals and precipitating other minerals. In this activity,
we label these “hydrothermally altered” sedimentary rocks as metamorphic, because the hightemperature and somewhat high-pressure process of alteration changed or metamorphosed the
original sedimentary rocks.
Additional Notes
Students may question the path from the Earth’s Surface (where weathering and erosion take
place) to Compaction and Cementation, without first going through Sediments. One example of
this is the formation of a rock called gossan (an iron-rich rock resulting from the weathering of
sulfide-bearing minerals). Oxygen dissolved in rain water oxidizes sulfide minerals, particularly
pyrite (FeS2), to form sulfuric acid (H2SO4), which leaches many of the elements from the original
rock (whether sedimentary, igneous, or metamorphic), leaving behind a rock that mostly contains the
minerals goethite (FeOOH) and hematite (Fe2O3). In this activity, we consider gossan a sedimentary
rock. Although it has changed from its original mineralogy and texture, it did not undergo any hightemperature or high-pressure mineralogical or textural changes that form metamorphic rocks.
Another example is a supergene enrichment blanket, which sometimes forms at the top of a copper
deposit. In this case, copper, which is dissolved by the same weathering process that forms gossan, is
redeposited below the groundwater table upon reaction with sulfide minerals. It changes the
mineralogy of the rock by depositing copper sulfide minerals (covellite, CuS, and chalcocite, Cu2S),
and it increases the copper grade and value of the ore.
Another example is hardened laterite (iron-oxide-rich, silica-poor soil commonly found in tropical
climates). Most laterite is unconsolidated soil, but when hardened by cementation with goethite or
hematite, it would be considered a rock.
In some instances, particularly in and near ore deposits, it is often difficult to determine what a rock
was before it was altered by either hot water or cold water.
Page 6
Next Generation Science Standards: The most applicable standards are
 High School - History of Earth HS-ESS2-1. Students who demonstrate understanding can
develop a model to illustrate how Earth’s internal and surface processes operate at different
spatial and temporal scales to form continental and ocean-floor features.
 High School – Science and Engineering Practices – Analyzing and Interpreting Data. Apply
concepts of statistics and probability to scientific and engineering questions and problems,
using digital tools when feasible.
 Middle School – Earth’s Systems MS-ESS3-1. Students who demonstrate understanding can
construct a scientific explanation based on evidence for how the uneven distribution of
Earth’s mineral, energy, and groundwater resources are the result of past and current
geoscience processes.
 Middle School – Earth’s Systems MS-ESS2-1. Students who demonstrate understanding can
develop a model to describe the cycling of Earth’s materials and the flow of energy that drives
this process.
 Disciplinary Core Ideas ESS2.A (Earth Materials and Systems), ESS2.B (Plate Tectonics and
Large-Scale Interactions), ESS2.C (The Roles of Water in Earth’s Surface Processes),
ESS3.A (Natural Resources).
This activity was adapted by J.G. and E.M. Price of the Education Committee of the Nevada Mining
Association from one created by Pamela Wilkinson of the Lowell Institute for Mineral Resources at
the University of Arizona, with funding from the Mining Foundation of the Southwest. This version
is dated 9 September 2016.
The next twelve pages are the station labels.
Following those pages are a one-page diagram of the rock cycle and
illustrations that help explain where different rock types and ores occur
in plate-tectonic settings.
The final pages are for the students, including optional examples of
completed rock-cycle data sheets and geologic history sheets.
Page 7
Intrusive Igneous Rock
Roll:
Number of years:
Roll: Go to:
2
100,000,000
2
High Temperature & Pressure
3
1,000,000
3
Earth’s Surface
4
10,000,000
4
Intrusive Igneous Rock
5
15,000,000
5
High Temperature & Pressure
6
35,000,000
6
Earth’s Surface
7
50,000,000
7
Intrusive Igneous Rock
8
100,000,000
8
Melting
9
5,000,000
9
High Temperature & Pressure
10
500,000,000
10
Intrusive Igneous Rock
11
500,000
11
Earth’s Surface
12
35,000,000
12
Melting
Adapted by the Education Committee of the Nevada Mining Association from the Lowell Institute for Mineral
Resources at the University of Arizona, with funding from the Mining Foundation of the Southwest.
Sedimentary Rock
Roll:
Number of years:
Roll: Go to:
2
10,000,000
2
Earth’s Surface
3
500,000
3
Melting
4
20,000,000
4
Sedimentary Rock
5
1,000,000
5
Melting
6
10,000,000
6
Earth’s Surface
7
100,000,000
7
Sedimentary Rock
8
1,000,000
8
High Temperature & Pressure
9
50,000,000
9
Earth’s Surface
10
10,000,000
10
Sedimentary Rock
11
500,000,000
11
Earth’s Surface
12
500,000
12
High Temperature & Pressure
Adapted by the Education Committee of the Nevada Mining Association from the Lowell Institute for Mineral
Resources at the University of Arizona, with funding from the Mining Foundation of the Southwest.
Metamorphic Rock
Roll:
Number of years:
Roll: Go to:
2
500,000,000
2
Melting
3
250,000,000
3
Earth’s Surface
4
200,000,000
4
Metamorphic Rock
5
10,000,000
5
Melting
6
100,000,000
6
Earth’s Surface
7
50,000,000
7
Metamorphic Rock
8
10,000,000
8
High Temperature & Pressure
9
100,000,000
9
Melting
10
75,000,000
10
Metamorphic Rock
11
500,000,000
11
Earth’s Surface
12
250,000,000
12
High Temperature & Pressure
Adapted by the Education Committee of the Nevada Mining Association from the Lowell Institute for Mineral
Resources at the University of Arizona, with funding from the Mining Foundation of the Southwest.
Volcanic Rock & Volcano
(Extrusive Igneous Rock & Location)
Roll:
Number of years:
Roll: Go to:
2
100,000
2
Earth’s Surface
3
10,000,000
3
Melting
4
50,000,000
4
Volcanic Rock & Volcano
5
10,000,000
5
Earth’s Surface
6
50,000
6
Melting
7
1,000,000
7
High Temperature & Pressure
8
100,000
8
Volcanic Rock & Volcano
9
10,000
9
Earth’s Surface
10
15,000,000
10
Volcanic Rock & Volcano
11
1,000
11
Melting
12
50,000
12
Volcanic Rock & Volcano
Adapted by the Education Committee of the Nevada Mining Association from the Lowell Institute for Mineral
Resources at the University of Arizona, with funding from the Mining Foundation of the Southwest.
Magma (Constituent)
Roll:
Number of years:
Roll: Go to:
2
5,000,000
2
Volcanic Rock & Volcano
3
10,000
3
Cooling & Crystallizing
4
50,000
4
Volcanic Rock & Volcano
5
100,000
5
Cooling & Crystallizing
6
1,000,000
6
Volcanic Rock & Volcano
7
500,000
7
Cooling & Crystallizing
8
5,000,000
8
Volcanic Rock & Volcano
9
75,000
9
Cooling & Crystallizing
10
10,000,000
10
Volcanic Rock & Volcano
11
100,000
11
Cooling & Crystallizing
12
1,000,000
12
Volcanic Rock & Volcano
Adapted by the Education Committee of the Nevada Mining Association from the Lowell Institute for Mineral
Resources at the University of Arizona, with funding from the Mining Foundation of the Southwest.
Sediments (Constituent)
Roll:
Number of years:
Roll: Go to:
2
5,000
2
Sediments
3
10,000
3
Compaction & Cementation
4
50,000
4
Water: River/Lake/Ocean
5
100,000
5
Compaction & Cementation
6
500,000
6
Earth’s Surface
7
1,000,000
7
Sediments
8
5,000
8
Water: River/Lake/Ocean
9
10,000
9
Earth’s Surface
10
5,000,000
10
Compaction & Cementation
11
100,000
11
Sediments
12
500,000
12
Water: River/Lake/Ocean
Adapted by the Education Committee of the Nevada Mining Association from the Lowell Institute for Mineral
Resources at the University of Arizona, with funding from the Mining Foundation of the Southwest.
Earth’s Surface: Weathering & Erosion
(Location & Process)
Roll:
Number of years:
Roll: Go to:
2
10,000
2
Earth’s Surface
3
100,000
3
Sediments
4
50,000
4
Water: River/Lake/Ocean
5
1,000,000
5
Sediments
6
100,000
6
Earth’s Surface
7
500,000
7
Sediments
8
10,000
8
Water: River/Lake/Ocean
9
1,000,000
9
Compaction & Cementation
10
500,000
10
Earth’s Surface
11
100,000
11
Compaction & Cementation
12
1,000,000
12
Water: River/Lake/Ocean
Adapted by the Education Committee of the Nevada Mining Association from the Lowell Institute for Mineral
Resources at the University of Arizona, with funding from the Mining Foundation of the Southwest.
Cooling & Crystallizing
(Process)
Roll:
Number of years:
Roll: Go to:
2
10,000
2
Intrusive Igneous Rock
3
500,000
3
Cooling & Crystallizing
4
750,000
4
Intrusive Igneous Rock
5
500,000
5
Cooling & Crystallizing
6
100,000
6
Intrusive Igneous Rock
7
250,000
7
Cooling & Crystallizing
8
10,000
8
Melting
9
500,000
9
Intrusive Igneous Rock
10
100,000
10
Melting
11
500,000
11
Intrusive Igneous Rock
12
100,000
12
Melting
Adapted by the Education Committee of the Nevada Mining Association from the Lowell Institute for Mineral
Resources at the University of Arizona, with funding from the Mining Foundation of the Southwest.
High Temperature & Pressure
(Process)
Roll:
Number of years:
Roll: Go to:
2
10,000,000
2
High Temperature & Pressure
3
100,000,000
3
Melting
4
50,000,000
4
Metamorphic Rock
5
100,000,000
5
Melting
6
10,000,000
6
High Temperature & Pressure
7
150,000,000
7
Metamorphic Rock
8
50,000,000
8
High Temperature & Pressure
9
200,000,000
9
Melting
10
100,000,000
10
Metamorphic Rock
11
200,000,000
11
Melting
12
50,000,000
12
High Temperature & Pressure
Adapted by the Education Committee of the Nevada Mining Association from the Lowell Institute for Mineral
Resources at the University of Arizona, with funding from the Mining Foundation of the Southwest.
Compaction & Cementation
(Process)
Roll:
Number of years:
Roll: Go to:
2
10,000
2
Sedimentary Rock (clastic)
3
50,000
3
Compaction & Cementation
4
500,000
4
Sedimentary Rock (clastic)
5
10,000,000
5
Compaction & Cementation
6
15,000,000
6
Sedimentary Rock (clastic)
7
100,000
7
Compaction & Cementation
8
10,000
8
High Temperature & Pressure
9
50,000
9
Sedimentary Rock (clastic)
10
1,000,000
10
High Temperature & Pressure
11
10,000,000
11
Sedimentary Rock (clastic)
12
15,000,000
12
High Temperature & Pressure
Adapted by the Education Committee of the Nevada Mining Association from the Lowell Institute for Mineral
Resources at the University of Arizona, with funding from the Mining Foundation of the Southwest.
Water: River/Lake/Ocean
(Location & Process—dissolution/precipitation)
Roll:
Number of years:
Roll: Go to:
2
10,000
2
Water: River/Lake/Ocean
3
1,000,000
3
Sediments
4
500,000
4
Sedimentary Rock (chemical)
5
5,000
5
Sediments
6
10,000
6
Compaction & Cementation
7
50,000
7
Water: River/Lake/Ocean
8
100,000
8
Sedimentary Rock (chemical)
9
1,000
9
Compaction & Cementation
10
10,000
10
Sediments
11
5,000
11
Water: River/Lake/Ocean
12
100,000
12
Sedimentary Rock (chemical)
Adapted by the Education Committee of the Nevada Mining Association from the Lowell Institute for Mineral
Resources at the University of Arizona, with funding from the Mining Foundation of the Southwest.
Melting
(Process)
Roll:
Number of years:
Roll: Go to:
2
20,000
2
Melting
3
5,000,000
3
Magma
4
50,000
4
Cooling & Crystallizing
5
100,000
5
Magma
6
1,000,000
6
Cooling & Crystallizing
7
500,000
7
Melting
8
100,000
8
Magma
9
5,000,000
9
Cooling & Crystallizing
10
10,000
10
Magma
11
20,000
11
Melting
12
1,000,000
12
Magma
Adapted by the Education Committee of the Nevada Mining Association from the Lowell Institute for Mineral
Resources at the University of Arizona, with funding from the Mining Foundation of the Southwest.
The following page is the rock-cycle diagram.
The final color pages can be used in a PowerPoint presentation
or overhead projection to explain where different rock types
and ores occur in plate-tectonic settings.
The following pages are to give to the students.
Rock Cycle and Mineral Deposits
The rock cycle helps us understand and visualize how rocks and minerals on Earth change from one
rock type to another (igneous, metamorphic, and sedimentary). The theory of plate tectonics explains
the details of the rock cycle and helps us understand the mechanisms and processes that move rocks
and minerals through the cycle. This exercise is designed to extend your understanding of both the
rock cycle and plate tectonics. It will also provide you with insight into the formation of mineral and
rock deposits (ores) on which we depend for the materials we use in our daily lives. Beginning with
the alarm clock that awakens us to the light bulbs that illuminate the room before we go to bed,
everything we use is made with, made by, or processed by the materials that come from mines. In
this exercise we are focusing on a few types of ores that are mined in the United States: sand and
gravel and placer gold in unconsolidated sediments; barite, diatomite, gypsum, iron, lead, limestone,
phosphate, potash, salt, uranium, and zinc in sedimentary rocks; hydrothermal gold in volcanic rocks;
porphyry copper and molybdenum, platinum, and rare-earth-element deposits in intrusive igneous
rocks, and Carlin-type (also hydrothermal) gold and crushed stone deposits in metamorphic rocks.
Procedure:
Working with a partner, you will ride the rock cycle recording your route and creating your geologic
history. Then determine whether you may have ever been an ore deposit.
1. Work in teams of two. Each team starts at a rock station – either volcanic rock, intrusive
igneous rock, metamorphic rock, or sedimentary rock. Consider yourself a small piece of
that rock—an atom in one of the minerals in the initial rock. Although you’ll remain the same
atom (unless you were radioactive), you’ll be changed into different solid, liquid, or gaseous
forms as you move through the rock cycle.
2. Record the rock type on the rock-cycle data sheet. Roll the dice, record the total number
rolled (possible numbers are 2 through 12) and the corresponding number of years on the first
line of the rock-cycle data sheet.
3. Roll the dice again, record the total number rolled and where that roll is taking you (“Go to”)
on the second line of the rock-cycle data sheet. Note that it could be where you already are.
Also circle on this line whether this is a Process, Location, Constituent, and/or Rock.
Processes include compaction and cementation (converting loose, unconsolidated sediment,
shells, or rock fragments into solid rock), high temperature and pressure (generally
achieved with deep burial, thrusting of one package of rocks on top of another, or subduction
in an oceanic trench), melting (either deep in the crust or mantle or near the surface), cooling
and crystallization, weathering and erosion (at the Earth’s surface, driven largely by energy
from the Sun), and dissolution and precipitation (occasionally resulting in chemical
sedimentary rocks, including gypsum, halite, barite, and some limestones).
4. If you are going to another station, go to that station.
5. If you have rolled a total number that keeps you at your current station, roll the dice again,
and record the number of years you will be there on the same line.
6. If you have moved to another station, roll the dice when you get there to determine how long
you are staying at that station (and record that number of years on the same line).
7. Continue to roll and record your data in this manner (repeating steps 3 through 6) until you
have become three separate rocks. You start out as a rock, go through some processes,
become another rock, go through additional processes, and become a final (third) rock. Be
sure to roll a final time to determine how long you stay as this final rock. Keep in mind that
you may stay at a particular station through multiple rolls. (See the example rock-cycle data
Page 1
sheets that are attached.) If you are running out of space on your data sheet, you can use the
“Sediments” station as one of your three rocks. Some teams will finish before others, as their
cycle may be shorter than others. That is okay.
8. Once you have data for three different rocks, sit back at your desk and write up the geologic
history of the rocks on the geologic history sheet, using your rock-cycle data sheet.
9. Understand that the rock station where you ended is the rock that you are right now (the
present); it is the youngest rock. Its age is from the present to however many years you rolled
in the last roll on the data sheet. (See the example geologic history sheets that are also
attached. Essentially the geologic history turns the rock-cycle data sheet upside down. Start at
the bottom and work your way up.) The oldest rock in your geologic history will be the rock
at which you started.
10. If you stayed at one station multiple times, add the number of years at which the dice
indicated that you stayed at that station. This combination will be what you enter on your
geologic history sheet.
11. Record the youngest rock (where you ended) at the top of the geologic history sheet and write
the number of years you stayed as this final rock.
12. Work your way from the bottom of the rock-cycle data sheet, one station at a time. On the
geologic history sheet, record the station and the number of years that you were at that station.
The rock at which you started (the oldest rock) will be on the bottom of the geologic history
sheet.
13. To determine the geologic age of each of your rocks, you will need to do some addition. The
youngest rock’s age is from present to the number of years on the top line of the geologic
history sheet. Record this at the bottom of the sheet on the line for the youngest rock.
14. Now determine the age of the middle rock. Add all the years from the top of the geologic
history sheet down to the line just above where that rock shows. This is the youngest age for
that rock. Now add the number of years that rock existed to this number, and you have the
oldest date for the middle rock. Record the name of this (middle) rock type and those two
numbers on the line for the middle rock on the geologic history sheet. The age of the oldest
rock is determined by adding all the years on the geologic history sheet except the number of
years on the last line, which is the youngest age that the oldest rock was. Finally, add the last
line of years to those years; this is the final age of the oldest rock.
15. Whew…now you have data that you can interpret to see whether one or more of your rocks
may have been a rock that could be mined!
16. To determine if one of your rocks could also be an ore (a rock that can be mined profitably),
look at the rock types and their ages listed in Table 1. Compare these rock types and ages
with your data.
Interpretation:
1. Where did you spend most of your time? __________________________________________
2. Why do scientists call the rock cycle a cycle? ______________________________________
___________________________________________________________________________
3. Where do weathering and erosion occur? __________________________________________
4. List the processes that move rocks through the rock cycle. ____________________________
___________________________________________________________________________
5. Explain the forces or sources of energy that create these processes. _____________________
___________________________________________________________________________
___________________________________________________________________________
6. If you were at the Earth’s surface, what type of rock were you when you got there? ________
Page 2 ___________________________________________________________________________
Generally, a rock must be at or near (within a few kilometers of) the Earth’s surface to be
considered an ore—a rock that can be profitably mined. To figure out whether your rocks
may have also been an ore deposit, determine whether your rock was present at one of the
times in Table 1. For example, if you were an intrusive igneous rock between 35,000,000 and
100,000,000 years ago (35 to 100 Ma), you could have formed a porphyry copper deposit
(like ones in Arizona, Montana, Nevada, New Mexico, and Utah).
Table 1. Examples of ores in the United States of America.
Rock type or constituent
Type of ore
Age range*
Location#
____________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ ________
Sediments
Sediments
Sedimentary rock (clastic)
Sedimentary rock (chemical)
Sand and gravel
Placer gold
Diatomite
Gypsum & Salt
Barite
Limestone
<10,000 years ago (Holocene)
<5.3 Ma (Holocene to Pliocene)
5.3 to 23 Ma (Miocene)
5.3 to 23 Ma (Miocene)
or 145 to 201 Ma (Jurassic)
or 252 to 299 Ma (Permian)
or 419 to 445 Ma (Silurian)
2.6 to 23 Ma (Pliocene to Miocene)
or 252 to 299 Ma (Permian)
252 to 299 Ma (Permian)
5.3 to 201 Ma (Miocene to Jurassic)
299 to 323 Ma (Pennsylvanian)
or 34 to 144 Ma (Eocene to Cretaceous)
359 to 419 Ma (Devonian)
252 to 541 Ma (Paleozoic)
HAWCE
AWE
W
W
WC
WC
E
E
W
W
WC
CE
W
W
AWCE
Sedimentary rock (chemical)
Phosphate
Sedimentary rock (chemical)
Sedimentary rock (clastic)
Sedimentary rock (clastic)
Potash/potassium
Uranium
Coal
Sedimentary rock (chemical)
Sedimentary rock (chemical
or clastic)
Sedimentary rock (chemical
or clastic)
Sedimentary rock (chemical)
Volcanic rock
Intrusive igneous rock
Intrusive igneous rock
Intrusive igneous rock
Lead and zinc
252 to 419 Ma (Permian to Devonian)
ACE
Iron
Hydrothermal gold
Porphyry copper
Porphyry molybdenum
Platinum
1,600 to 2,500 Ma (Paleoproterozoic)
2.6 to 56 Ma (Pliocene to Eocene)
34 to 201 Ma (Eocene to Jurassic)
23 to 56 Ma (Oligocene to Eocene)
2,500 to 4,000 Ma (Archean)
or 1,000 to 1,600 Ma (Mesoproterozoic)
1,000 to 1,600 Ma (Mesoproterozoic)
34 to 56 Ma (Eocene)
>541 Ma (Precambrian)
C
AW
AW
W
W
C
W
W
WCE
Intrusive igneous rock
Metamorphic rock
Metamorphic rock
Rare earth elements
Carlin-type gold
Crushed stone (gneiss)
____________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________
* Ma = millions of years ago. # H = Hawaii; A = Alaska; W = western, C = central, E = eastern United States.
7. Look at your data. Pay attention to where you are located geographically (either Alaska,
Hawaii, or the western, central, or eastern conterminous United States. Could you have
formed any of the above ore deposits? If so, which ones?
___________________________________________________________________________
___________________________________________________________________________
8. Assuming that you did form an ore deposit, was the deposit preserved and located near the
surface so that it can now be mined? Or was the deposit weathered and eroded away in the
years after it formed?
___________________________________________________________________________
___________________________________________________________________________
9. Take a survey in your class and list the number and types of ore deposits formed through this
activity by everyone in the class.
___________________________________________________________________________
Page 3
10. Did this exercise help you understand how infrequently economic accumulations or rocks and
minerals occur? _____ Explain. _________________________________________________
___________________________________________________________________________
___________________________________________________________________________
11. What is the probability that on your first roll of the dice you stay at the rock at which you
start? ___________________
To answer this question, you need to know the probabilities of possible rolls of the dice.
The probability of any one of the six numbers on a six-sided die is 1/6 or 0.1667 or 16.67%
(rounded to four significant figures), assuming that the die isn’t loaded (weighted so that one
number preferentially is rolled) or damaged such that the roll is not random.
The probability of one event occurring and a second event occurring is equal to the
probability of the first event occurring multiplied by the probability of the second event
occurring. Therefore the probability of rolling, for example, a 1 with the first die and a 1 with
the second die is 1/6 x 1/6 = 1/36. Similarly, the probability of rolling a 1 with the first die
and a 2 with the second die is 1/6 x 1/6 = 1/36, and the probability of rolling a 2 with the first
die and a 1 with the second die is also 1/6 x 1/6 = 1/36.
The probability of one event occurring or a second event occurring is equal to the probability
of the first event occurring added to the probability of the second event occurring. Therefore
the probability of rolling a total of 3 with one roll of two dice is 1/36 + 1/36 = 2/36. Using the
same rules, Table 2 lists the probabilities for the eleven possible numbers that can be rolled
with two dice.
Table 2. Probabilities of possible rolls of two six-sided dice.
__________________________________________________________________________________________
Role
Possible combinations of dice
Probability
2
1&1
1/36
3
1 & 2 or 2 & 1
2/36
4
1 & 3 or 3 & 1 or 2 & 2
3/36
5
1 & 4 or 4 & 1 or 2 & 3 or 3 & 2
4/36
6
1 & 5 or 5 & 1 or 2 & 4 or 4 or 2 or 3 & 3
5/36
7
1 & 6 or 6 & 1 or 2 & 5 or 5 & 2 or 3 & 4 or 4 & 3
6/36
8
2 & 6 or 6 & 2 or 3 & 5 or 5 & 3 or 4 & 4
5/36
9
3 & 6 or 6 & 3 or 4 & 5 or 5 & 4
4/36
10
4 & 6 or 6 & 4 or 5 & 5
3/36
11
5 & 6 or 6 & 5
2/36
12
6&6
1/36
______________________________________________________________________________________________________________________________________________________________________________________ ____________________________________________
12. What is the least number of rolls of the dice that are needed to complete this exercise? It will
help to examine the rock-cycle diagram and to remember that you also must roll for the
number of years at each station._______________________
Page 4
13. For which starting rock do you have the highest probability of completing this exercise with
the least number of rolls? __________________ What path does your atom take for this
highest probability? __________________________________________________________
___________________________________________________________________________
14. Starting as an atom in a volcanic rock, what is the probability that you will
a. be there for 50,000 years,
___________________________
b. then go to the Earth’s Surface,
___________________________
c. be there for 500,000 years,
___________________________
d. then go to Sediments,
___________________________
e. be there for 500,000 years,
___________________________
f. then go to Compaction and Cementation,
___________________________
g. be there for 10,000,000 years,
___________________________
h. then go to Sedimentary Rock (clastic),
___________________________
i. be there for 100,000,000 years,
___________________________
j. stay there (at Sedimentary Rock) on the next roll,
___________________________
k. be there for 100,000,000 more years,
___________________________
l. stay there (at Sedimentary Rock) on the next roll,
___________________________
m. be there for 100,000,000 more years,
___________________________
n. then go to High Temperature & Pressure,
___________________________
o. be there for 100,000,000 years,
___________________________
p. then go to Metamorphic Rock, and, finally,
___________________________
q. be there for 50,000,000 years?
___________________________
That is, what is the overall probability of all these steps occurring in this sequence?
________________________________________________________________________
Example 3 is one scenario of rolls of the dice by which these steps could have occurred.
This is a practical example. In the end, you will be an atom in a Metamorphic Rock, which,
upon examination of Table 1, is the right age to have a Carlin-type gold deposit. This type of
ore deposit is named for the town of Carlin, Nevada, near which several of these types of
deposits occur. Similar deposits occur in Utah and other parts of the world. The ones in the
western United States formed by hot water, laden with gold and sulfur and heated by Eocene
magmas related to subduction of oceanic crust beneath the North American Plate. The hot
water also altered the sedimentary host rocks by dissolving some minerals and precipitating
other minerals. In this activity, we label these “hydrothermally altered” sedimentary rocks as
metamorphic, because the high-temperature and somewhat high-pressure process of alteration
changed or metamorphosed the original sedimentary rocks.
Page 5